The invention relates to a floor nozzle for vacuum cleaners.
A known floor nozzle of this kind (DE-GM 73 43 139) comprises a suction channel arranged in the front area of the lower nozzle part and extending over the width of the nozzle. In its central area, the suction channel is divided into two partial channels by a flexible or elastic cross-piece, the latter being interrupted in the area of the suction opening in the bottom piece of the floor nozzle. In its rest position, the elastic strip projects a little beyond the bottom of the nozzle which enables it, due to its elasticity, to yield in the direction of movement, i.e. to turn in a forward or backward direction so that it comes to apply itself flat upon the entire surface to be cleaned, which effect can be achieved even on irregular surfaces. The main reason for giving the cross-piece this elastic design is to enable the cross-piece, which preferably consists of an elastic material, to give way laterally; thus, less pushing force is required as the cross-piece simply turns to the rear as viewed in the pushing direction.
According to another known design (DE-GM 19 43 044) of a vacuum cleaner nozzle it has been known to provide two suction slots arranged one behind the other in the working direction of the nozzle. In this case the suction slots slide on the surface to be cleaned by their leading and trailing longitudinal edges, while the inner longitudinal edges of the suction slots include between them an air channel which extends over the full width of the nozzle and is open on the narrow ends thereof. It is the purpose of this arrangement to enable the air to freely enter this central intermediate channel--which is not connected to the suction opening of the nozzle--from both sides and be taken in through the suction slots practically from the inside. This has the practical effect of guiding the suction flow toward the suction opening across four longitudinal edges that slide on the surface to be cleaned and that, besides, all lie in one and the same plane.
In addition, the outwardly open, free intermediate air channel may be equipped with some conventional lint pickup means, for example in the form of a comb.
The problem encountered with conventional suction nozzles, in particular when cleaning rugs or other deep-pile materials, namely to separate the nap so as to achieve a deep cleaning effect, cannot be achieved in this way as both the elastic cross-piece according to DE-GM 73 43 139 and necessarily also the four longitudinal edges of DE-GM 19 43 044 only slide on the surface to be cleaned and do not have the effect to separate its nap.
Still other embodiments of known floor nozzles for vacuum cleaners have been described by the following publications according to DE-OS 32 41 213, DE-OS 29 39 353, EP 01 63 772, DE-=OS 32 28 644, AT 236 595, DE-GM 88 09 802, GB 22 00 538, DE-OS 34 31 164 and DE-GM 78 13 344.
The design described by DE-OS 32 41 213 comprises adjustable runners including between them strips provided each with a soft coating. The runners serve as carrier elements which, in the rest position, are set back relative to the supporting surfaces of the strips by the same predetermined amount by which they project beyond the same supporting surface in their operative position. Inside the strips, channels extending transversely to the longitudinal axis are provided in staggered arrangement, as between neighboring strips.
From DE-GM 88 09 802 it has been further known to design a vacuum cleaner nozzle, which is supported on rear support rollers 9, in such a way that the swivel axis for a coupling pipe is located vertically above the axis of rotation of the support wheel, while the tilt axis of the nozzle opening is located below the axis of rotation of the support wheels and --in horizontal direction--before these support wheels in the direction of the longitudinal center axis. Thus, pushing of the vacuum cleaner nozzle will simultaneously result in an overturning moment acting on an intermediate channel piece. This overturning moment will produce at the nozzle a vertical force acting in a downward direction, which is transmitted to the nozzle piece via the tilt axis so as to press the nozzle piece against the surface to be cleaned. However, the operator cannot in this case--as is sometimes tried--apply more pressure on the coupling pipe, by means of which the vacuum cleaner nozzle is moved across the floor by the operator, in order to press it more firmly against the surface to be worked--which would of course be desirable--as all forces exerted by the operator in downward direction are absorbed by the support wheels. In the case of another known vacuum cleaner nozzle (DE-OS 28 17 512), suction channels opening in a fork-like manner extend on both sides of a central suction opening in the bottom plate which transitions into the pivotal suction pipe, via an exhaust channel. The suction channels are configured as recessed portions in the bottom plate and are surrounded on all sides by surfaces which in the rug-cleaning position simultaneously serve as support surfaces for the nozzle plate. At the front and at the rear--viewed in the pushing direction--a retractable hard-floor brush strip extends over the full width of the vacuum cleaner nozzle, and in addition a usual lint pickup rectangle made from a carpet-like fabric with inclined bristles is provided behind the suction opening as viewed in the forward pushing direction.
In the case of another vacuum cleaner nozzle according to European Patent Specification No. 0 151 739, a pair of wheels of the kind normally provided for supporting the pipe connecting the handle with the intake pipe and the floor nozzle, is arranged coaxially with the pivot axis of the suction pipe, which latter is articulated on the floor nozzle. It is to be ensured in this way that the depth of penetration of the working edges defining the suction opening will be optimally adapted to different floorings and, especially, cannot be influenced by the force applied on the nozzle. Such a floor nozzle does not, therefore, respond to the force exerted by the user during the cleaning operation by penetrating deeper into or applying itself more strongly upon the floor to be cleaned, since the force so applied is completely absorbed by the pair of support wheels. This may, however, be a problem under certain circumstances when the user intentionally tries to increase the cleaning effect by applying more pressure.
It has further been known (European Patent Specification No. 0 163 772) to simplify the vertical adjustment of the brush strip arranged in front of the forward working edge of the nozzle base by disposing the brush strip on a rocker arm pivotally mounted in the rear area of the nozzle housing. The position of the rocker arm can be changed in the usual way by means of an actuator element provided on the nozzle housing, whereafter the rocker arm can be locked in the respective new position. The different positions of brush strip, thread or lint pickup means, which are adjustable in the present case, and of certain support surfaces relative to each other are firmly predetermined by the fact that three control slides are united to a single control member by connection pieces so that when one of the control elements is adjusted, the different operating elements of the vacuum cleaner nozzle will all be moved into relative positions determined by the geometry by the different interconnected control slides.
Now, it is the object of the present invention to achieve a substantial improvement of the cleaning effect of a floor nozzle for vacuum cleaners, especially in connection with nap floorings.